The Newark-Hartford astrochronostratigraphic polarity timescale (APTS) was developed using a theoretically constant 405-kiloyear eccentricity cycle linked to gravitational interactions with Jupiter-Venus as a tuning target and provides a major timing calibration for about 30 million years of Late Triassic and earliest Jurassic time. While the 405-ky cycle is both unimodal and the most metronomic of the major orbital cycles thought to pace Earth's climate in numerical solutions, there has been little empirical confirmation of that behavior, especially back before the limits of orbital solutions at about 50 million years before present. Moreover, the APTS is anchored only at its younger end by U-Pb zircon dates at 201.6 million years before present and could even be missing a number of 405-ky cycles. To test the validity of the dangling APTS and orbital periodicities, we recovered a diagnostic magnetic polarity sequence in the volcaniclastic-bearing Chinle Formation in a scientific drill core from Petrified Forest National Park (Arizona) that provides an unambiguous correlation to the APTS. New high precision U-Pb detrital zircon dates from the core are indistinguishable from ages predicted by the APTS back to 215million years before present. The agreement shows that the APTS is continuous and supports a stable 405-kiloyear cycle well beyond theoretical solutions. The validated Newark-Hartford APTS can be used as a robust framework to help differentiate provinciality from global temporal patterns in the ecological rise of early dinosaurs in the Late Triassic, amongst other problems.
|Original language||English (US)|
|Number of pages||6|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Jun 12 2018|
Bibliographical noteFunding Information:
ACKNOWLEDGMENTS. We thank the National Park Service, particularly superintendent Brad Traver, for permission to core in the park and for logistical support during site selection and drilling. On-site and laboratory core processing, scanning, and archiving were carried out by LacCore, particularly Anders Noren, Kristina Brady, and Ryan O’Grady; on-site core-handling volunteers Justin Clifton, Bob Graves, Ed Lamb, Max Schnurrenberger, and Brian Switek are thanked for their around-the-clock efforts, and drilling manager Doug Schnurrenberger for overseeing a superb coring project. We sincerely thank the two journal reviewers for insightful comments that allowed us to improve the data analyses. This project was funded by National Science Foundation (NSF) Collaborative Grants EAR 0958976 (to P.E.O. and J.W.G.), 0958723 (to R.M.), 0958915 (to R.B.I.), 0959107 (to G.E.G.), and 0958859 (to D.V.K.), and by Deutsche Forschungsgemeinschaft for International Continental Scientific Drilling Program support. Additional support was provided by NSF Grant EAR-1338583 (to G.E.G.) to the Arizona LaserChron Center; P.E.O. acknowledges support from the Lamont-Climate Center, R.M. acknowledges support of the Ann and Gordon Getty Foundation, and D.V.K. is grateful to the Lamont–Doherty Incentive Account for support of the Paleomagnetics Laboratory. Curatorial facilities for the work halves of the CPCP cores are provided by the Rutgers Core Repository. Any opinions, findings, or conclusions of this study represent the views of the authors and not those of the US Federal Government. This is a contribution to IGCP-632, and is Petrified Forest Paleontological Contribution 54, and Lamont–Doherty Earth Observatory Contribution 8208.
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